By Jay Landers
A new park featuring trails and a trio of pedestrian bridges is providing improved access to economic and recreational opportunities in Milwaukee, while at the same time collecting and storing storm-water runoff.
Situated along the south bank of the Menomonee River, Three Bridges Park was designed to facilitate public access to the waterway while also reducing bank erosion and improving fish habitat. Eddee Daniel
October 8, 2013—A new park opened in late July in Milwaukee is intended to reconnect economically distressed neighborhoods to the broader city, facilitating urban revitalization while helping to improve ecological conditions along the heavily modified Menomonee River. Located on the site of what once was an abandoned rail yard, the new park features trails and a trio of pedestrian bridges linking the facility to adjoining neighborhoods and offering residents improved access to economic and recreational opportunities. Known as Three Bridges Park, the 24 acre site also includes landscape features designed to resemble natural glacial landforms and a system for collecting and storing storm-water runoff underground before dispensing it to wetland-like habitats.
Located along the south bank of the Menomonee River and connected to an existing pedestrian trail system known as the Hank Aaron State Trail, Three Bridges Park is part of an ongoing effort to revitalize the 1,200 acre Menomonee River Valley, which was originally a wild rice marsh at the time of the founding of the City of Milwaukee. As the city grew, the marsh was filled in and the river was straightened and its course highly modified. By the late 19th century, the valley had become a thriving industrial area. Chief among the businesses operating there was the Milwaukee Road Shops, a rail car manufacturer that remained in business from 1879 to 1985 and employed a massive rail yard as part of its operations. Following the closure of the Milwaukee Road Shops and other area businesses during the latter decades of the 20th century, the Menomonee River Valley fell on hard economic times. Particularly hard hit were the adjoining neighborhoods that once housed the thousands of workers employed by the disappearing industries. As businesses withdrew, the area experienced urban blight in the form of abandoned buildings and contaminated land. Meanwhile, freeways were built all around the valley, and pedestrian connections that once linked nearby workers to valley jobs were removed. For decades, the valley was largely forgotten.
Located on the site of what once was an abandoned rail yard, Milwaukee’s new Three Bridges Park features trails and a trio of pedestrian bridges linking the facility to adjoining neighborhoods and offering residents improved access to economic and recreational opportunities. City of Milwaukee
In the late 1990s, a public-private partnership began working on a master plan to revitalize the entire valley. Central to this plan were the City of Milwaukee's purchase of the site of the former Milwaukee Road Shops and multiple efforts to revitalize the blighted areas and return jobs to the neighboring communities. Since 1999, more than 39 companies have moved to the valley, bringing more than 5,000 new jobs to the area. However, the valley topography and the built environment of freeways and rail operations left the nearby neighborhoods disconnected from that job growth, says Laura Bray, the executive director of Menomonee Valley Partners, Inc., a Milwaukee-based nonprofit organization dedicated to revitalizing the Menomonee River Valley.
Restoring such connections while improving environmental conditions have been major goals of the efforts to revitalize the Menomonee River Valley, Bray says. "The whole approach of the valley's redevelopment has been to try to link ecology, economy, and community together in really intentional and tangible ways," she says. Menomonee Valley Partners worked with the City of Milwaukee, the State of Wisconsin, and the Urban Ecology Center—a local environmental education group—to put together an effort that builds on the economic development achievements made to date. The $25-million effort includes construction of the new park, 6 mi of the Hank Aaron State Trail, and three bicycle and pedestrian bridges, as well as riverbank restoration and the renovation of a vacant tavern into a third branch of the Urban Ecology Center, which is using the new park as an outdoor science classroom for thousands of kids and families. To date, $22.8 million has been raised for this series of integrated projects.
Once part of the former rail yard, the site that is now Three Bridges Park lay vacant for decades, during which time significant quantities of construction debris and fill material were placed at the location. Because of its poor soils, narrow configuration, and dearth of supporting infrastructure, the spot offered little potential as a site for new businesses, Bray says. But as a park, the location held significant promise, including river access for recreation and fishing and the opportunity to connect to the Hank Aaron State Trail.
Even the presence of the construction debris and fill would prove useful in the park's development, as it afforded an opportunity to vary the topography on an otherwise flat landscape and create unique habitats. During the early conceptual phase of the project design, the design team worked with various groups, including the Urban Ecology Center and the Geology Department at the University of Wisconsin-Milwaukee, says Bill Zippel, P.E., S.E., M.ASCE, a project manager in the Milwaukee office of Alfred Benesch and Company, which has its headquarters in Chicago. The firm served as the project lead and was responsible for site layout and design, structural engineering, path geometry, and hydraulic analysis. Based on input from these groups, the design team opted to reconfigure the existing materials at the site so that they would resemble "natural glacial landforms present here in southeast Wisconsin," Zippel says. "We were able to manipulate the two main mounds to resemble glacial drumlins, and a large conical mound was added to resemble a kame." To guard against potential contamination in the materials, the glacial features were capped with a layer of clean soil and designed with side slopes having a maximum grade of 3:1 (horizontal to vertical).
To control storm-water runoff within the park, the design included two main swales to convey flows toward the river. Of these swales, the one that receives most of the water was "designed in a rather unique way," Zippel says. This swale leads to an underground storage system comprising six divided cells that are approximately 2,000 ft long and filled with stones. Water passing through the underground cells percolates among the stones, decreasing in temperature and depositing suspended solids. At the downstream end of the cells, an adjustable valve discharges water to a swale and a small wetland pond, essentially mimicking the form and function of a natural spring. As a result, "we anticipate that this wetland system will provide an opportunity to grow more rare and conservative native plants than are typically found in Milwaukee's urban landscape," Zippel says. Meanwhile, the project site has been planted with a seed mix designed to provide a diverse mix of hardy native vegetation.
As for river restoration efforts, the project sought to improve in-stream habitat and address erosion problems along the shoreline. Designed by Inter-Fluve, Inc., of Hood River, Oregon, the project's river restoration aspects included the use of stone point bars along the banks to vary the direction of flow during low-water conditions. In certain locations, boulders were added to diversify flow conditions and improve fish habitat. Meanwhile, the design also included measures to stabilize the shoreline and facilitate better access to the river. "Before construction, much of the south bank was a brushy, steep bank about twenty feet above the normal summer water line," Zippel says. In two locations, the steep bank was cut back, lowering it to a height of about 4 ft above the water line and enabling easy access to the river.
Along with 1 mi of hiking trails, the new park also features the three pedestrian bridges for which it is named. All three bridges are steel truss structures specially designed to have a non-redundant load path, Zippel says. "In some cases, the architectural enhancements were used as the non-redundant load paths," he says. For example, one of the bridges—a 14 ft wide, 160 ft long, covered span crossing the Menomonee River at the park's western end—includes an upturned member that is capable of providing a redundant load path to prevent collapse in the event that the bottom chord of the truss fails. Of the two other bridges, one is 12 ft wide and 161 ft long and crosses the river, while the other comprises a 12 ft wide, 279 ft long structure that is located at the park's eastern end and spans the railroad tracks that bound the park to the south.
Completed in November 2010, the westernmost bridge was constructed by Zenith Tech, Inc., of Waukesha, Wisconsin. The Lunda Construction Company, of Black River Falls, Wisconsin, constructed the other two bridges and the rest of the park's features. Wenk Associates, of Denver, was responsible for the overall landscape site design, while Marek Landscaping, LLC, of Milwaukee, designed the park's native landscape restoration plan. Three Bridges Park is owned cooperatively by the City of Milwaukee and the State of Wisconsin, with a land management and programming partnership in place with the Urban Ecology Center and Menomonee Valley Partners.